US4364113A - Crack development measuring equipment - Google Patents

Crack development measuring equipment Download PDF

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Publication number
US4364113A
US4364113A US06/179,519 US17951980A US4364113A US 4364113 A US4364113 A US 4364113A US 17951980 A US17951980 A US 17951980A US 4364113 A US4364113 A US 4364113A
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US
United States
Prior art keywords
crack
test piece
image
video
television
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/179,519
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English (en)
Inventor
Peter Sengebusch
Horst Nowack
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Deutsches Zentrum fuer Luft und Raumfahrt eV
Original Assignee
Deutsches Zentrum fuer Luft und Raumfahrt eV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Deutsches Zentrum fuer Luft und Raumfahrt eV filed Critical Deutsches Zentrum fuer Luft und Raumfahrt eV
Assigned to DEUTSCHE FORSCHUNGS- UND VERSUCHSANSTALT FUR LUFT- UND RAUMFAHRT E.V., A CORP. OF GERMANY reassignment DEUTSCHE FORSCHUNGS- UND VERSUCHSANSTALT FUR LUFT- UND RAUMFAHRT E.V., A CORP. OF GERMANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: NOWACK HORST, SENGEBUSCH PETER
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Publication of US4364113A publication Critical patent/US4364113A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination

Definitions

  • the invention relates to crack development measuring equipment with a loading device in which a test piece can be clamped, and an optical measuring tool trained on the test piece.
  • the problem of the invention is to provide crack development measuring equipment of the kind mentioned at the beginning which makes possible the measurement at the time being considered of material cracks along the test piece objectively and with great precision, and moreover operates at very high speed, so that the individual measurements are already available a short time afterwards and can, if necessary, be processed electronically.
  • the optical measuring tool prefferably has a television camera which is connected to a discriminator which converts the image points of the television image into binary pulses, for the discriminator to be connected to a store taking up the binary pulses of a television image and for a comparator to be provided which compares the contents of the store with the binary pulses of a consecutive television image.
  • the television camera monitors the material test piece surface and thus first of all produces a series of analogue video signals as well as the required sync signals. Video signals and sync signals are separated in the discriminator and the video signal digitized.
  • the digital (binary) video signals are stored in the store in the form of lines and dots. The store is of sufficient capacity to store a pulse for each image point of the television image. The storing of a television image occurs once at the start of the test and every time a crack measurement is to take place during the course of the test.
  • the video signal occurring at each crack measurement is supplied to one input of the comparator, the second input of which is connected with the output of the store.
  • a comparison then takes place in the comparator between the contents of the image storing locations and the corresponding instantaneous value of the video signal and the new image is filed in the image store. If no variations appear at the comparison, a NOT-pulse is issued. If, on the contrary, variations appear between the contents of the store and the additional television image monitored at a freely-selectable point of time, a YES-pulse is issued, i.e. a spreading of the fatigue crack has taken place. In this way it can be ascertained very quickly and reliably whether a crack has formed since the last measurement or whether a crack already existing has spread.
  • the number of non-coincident binary pulses of the compared television images is counted and indicated. There is obtained therewith, within the shortest time, reliable numerical data concerning the enlargement of the crack since the point of time of the last measurement.
  • a front microscope attachment is connected to the television camera.
  • a resolution of 2.5 ⁇ can be obtained when the television image has 120 lines, or a resolution of 1.25 ⁇ when the television image has 240 lines.
  • the line direction of the television camera is at right angles to the direction of the crack and the comparison of the television images takes place through linear comparisons.
  • the crack extension may also be quantitatively determined by the number of lines in which a change in the picture content has taken place compared with the last analysis. These lines can be counted.
  • the television camera is mounted on a sliding carriage which can be moved under control in three planes passing at right angles to one another.
  • the control of the sliding carriage may ensue as a function of the measured crack enlargement. In that way it is ensured that there always appears in the television image that part of the test piece which is of interest for the measurement or in which the crack enlargement takes place. If, for example the crack approaches the left-hand edge of the television image, the camera is moved a definite amount to the right. If the crack expands during the course of the test, there is a following movement of the camera in the crack expansion direction by a definite amount, exactly parallel to the test piece. The range of the depth of focus is kept constant with the help of a receiver.
  • the loading of the crack development test piece is controlled in such a way that the loading of the test piece is at a standstill for a short time during the taking of the additional television image. In this way it is ensured that the measurements are not falsified through oscillatory movements of the test piece. As the measurement requires only a very short time (maximum 40 ms), only a very short stoppage is necessary for the measurement.
  • a test piece 11 is clamped vertically in the loading device denoted 10.
  • the loading device 10 has at its lower end a test cylinder 11 which produces tensile, compressive or vibratory loads along the test piece.
  • a device 12 for measurement of the load is mounted at the upper holder of the test piece.
  • the pressure gauge 12 is connected with one input of a variable-gain amplifier 13, the output signal from which controls the valve of the test cylinder 11.
  • At the other input of the control amplifier 13 are the output signal of a function generator 14 for the nominal value as well as the control signal of the measuring cycle program control 15.
  • the front microscope attachment 16 of the television camera 17 is directed on to a part of the surface of the test piece 11.
  • the television camera 17 thus takes an image of the respective part of the test piece 11 and supplies this together with the sync signals to the discriminator 18.
  • the discriminator 18 delivers the image and sync signals to a monitor 19 at which the input television image is made visible.
  • the discriminator 18 contains a device for producing a reference grid on the monitor 19. This reference grid, which consists of horizontal and vertical strips, facilitates the adjustment of the television camera with reference to the test piece surface zone to be accommodated.
  • the discriminator 18 moreover separates the image pulses from the sync pulses of the television camera 17 and digitizes the image pulses with the help of a threshold circuit, so that in the case of the image pulses discrimination is between black and white only.
  • These binary image pulses, which occur at the output 20 of the discriminator 18, are supplied to the store 21 and the comparator 22.
  • the store in the case of 120 units of measurement, has a minimum storage capacity of 10K and is therewith capable of holding all image points of the television image.
  • the store thus retains the television image last taken.
  • the television image contained in the store 21 is compared with the next following television image in order to ascertain whether or not the two television images are identical.
  • the comparison of the two television images in the comparator 22 can take place by linear comparison. If two lines do not coincide, then the crack has continued inside these lines.
  • the output of the comparator is connected with a microprocessor 23 for operational control and data processing and the microprocessor output is connected to a data output unit 24.
  • the microprocessor 23 contains a counter which counts those lines in which there is not coincidence between the two television images. The meter indication of this counter thus represents the crack development since the last measurement.
  • the data output may take place by means of a pointer, the crack length, the number of load cycles, the crack velocity, the measuring instalment number, the clock time, etc. being indicated.
  • the microprocessor establishes, beyond that, whether the crack is approaching one of the edges of the television image, and controls in dependence thereon, the motor drive 28 for the position control of the television camera 17 with the front microscope attachment 16.
  • a distance recorder 25 is coupled with the front microscope attachment 16 and determines distance of the front microscope attachment 16 from the test piece 11 and supplies this value to the motor drive 28. This actual value is compared with the desired value supplied from the microprocessor 23 and there is controlled as a function of the deviation, a sliding carriage on which is fixed the television camera 17 with the front microscope attachment and the distance recorder.
  • the sliding carriage (not shown) can travel in three planes extending at right angles to one another.
  • the microprocessor 23 also controls the measuring cycle program control 15 and, beyond this, line and frame sync circuit 26 for the television camera 17 in such a way that the taking of a television image results only when the load rests for a short time on the test piece.
  • the timing of the line and frame sync circuit 26, of the measuring cycle program control 15, of the discriminator 18, of the store 21 and of the microprocessor 23 takes place through a sync generator 27.
  • This may be a crystal-controlled oscillator.

Landscapes

  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
US06/179,519 1979-08-23 1980-08-19 Crack development measuring equipment Expired - Lifetime US4364113A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2934038 1979-08-23
DE2934038A DE2934038C2 (de) 1979-08-23 1979-08-23 Rißfortschritts-Meßeinrichtung

Publications (1)

Publication Number Publication Date
US4364113A true US4364113A (en) 1982-12-14

Family

ID=6079062

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/179,519 Expired - Lifetime US4364113A (en) 1979-08-23 1980-08-19 Crack development measuring equipment

Country Status (6)

Country Link
US (1) US4364113A (enrdf_load_stackoverflow)
JP (1) JPS5635006A (enrdf_load_stackoverflow)
DE (1) DE2934038C2 (enrdf_load_stackoverflow)
FR (1) FR2463926A1 (enrdf_load_stackoverflow)
GB (1) GB2057124B (enrdf_load_stackoverflow)
NL (1) NL181755C (enrdf_load_stackoverflow)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4486777A (en) * 1981-10-14 1984-12-04 Fuji Electric Company, Ltd. Defect detecting apparatus and method
US4488648A (en) * 1982-05-06 1984-12-18 Powers Manufacturing, Inc. Flaw detector
US4528593A (en) * 1981-10-23 1985-07-09 Nicol James C B Visual sensor systems
US4581706A (en) * 1982-01-25 1986-04-08 Hitachi, Ltd. Method and apparatus for testing a joint
US4653109A (en) * 1984-07-30 1987-03-24 Lemelson Jerome H Image analysis system and method
US4716459A (en) * 1985-01-25 1987-12-29 Nippon Kokan Kabushiki Kaisha Fatigue crack position detection apparatus
US4875170A (en) * 1986-04-10 1989-10-17 Hitachi, Ltd. Method and apparatus for estimating life expectancy of mechanical structures
US5060007A (en) * 1986-11-20 1991-10-22 Canon Kabushiki Kaisha Image blur display device
US5291279A (en) * 1990-08-27 1994-03-01 Toyoda Gosei Co., Ltd. Fatigue testing apparatus and method
US5539656A (en) * 1994-10-11 1996-07-23 United Technologies Corporation Crack monitoring apparatus
KR100387197B1 (ko) * 2000-08-03 2003-06-12 주식회사 비솔 고속 결함 검출 시스템 및 방법
US20050074140A1 (en) * 2000-08-31 2005-04-07 Grasso Donald P. Sensor and imaging system
US20070023485A1 (en) * 2005-07-29 2007-02-01 Snecma Method of repairing a blade of a one-piece bladed disc of a turbomachine and test piece for implementing the method
US7321699B2 (en) 2002-09-06 2008-01-22 Rytec Corporation Signal intensity range transformation apparatus and method
CN102661893A (zh) * 2012-05-08 2012-09-12 浙江工业大学 疲劳裂纹扩展试验摄像头安装调整机构
US20190064119A1 (en) * 2017-08-28 2019-02-28 Siemens Energy, Inc. Laser ultrasonic thermography inspection

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1196085A (en) * 1980-11-07 1985-10-29 John W.V. Miller Method and apparatus for detecting defects in glass bottles using event proximity
DE3426056A1 (de) * 1983-07-16 1985-01-24 Leicester Polytechnic, Leicester Verfahren und vorrichtung zur kontrolle von textilien
GB8331248D0 (en) * 1983-11-23 1983-12-29 Kearney & Trecker Marwin Ltd Inspecting articles
DE3440473A1 (de) * 1984-11-06 1986-05-07 Karl Deutsch Prüf- und Meßgerätebau GmbH + Co KG, 5600 Wuppertal Verfahren und vorrichtung zur feststellung von rissen auf der oberflaeche von werkstuecken
US4574642A (en) * 1984-11-23 1986-03-11 The Firestone Tire & Rubber Company Apparatus for automated crack growth rate measurement
GB2173300B (en) * 1985-04-06 1989-06-28 Schaudt Maschinenbau Gmbh Apparatus for optically monitoring the surface finish of ground workpieces
FR2580403B1 (fr) * 1985-04-11 1988-05-13 Syrov Alexandr Procede de determination des parametres d'une fissure et dispositif pour sa mise en oeuvre
JPH0695065B2 (ja) * 1987-03-02 1994-11-24 志朗 萩下 亀裂試験装置の亀裂進展追跡装置
GB2223319B (en) * 1988-10-03 1992-08-26 Rolls Royce Plc Method & means for fatigue testing
US4911017A (en) * 1989-04-21 1990-03-27 The Goodyear Tire & Rubber Company Multiple sample automated cut growth analysis
JPH0736001B2 (ja) * 1990-10-31 1995-04-19 東洋ガラス株式会社 びんの欠陥検査方法
DE19522247B4 (de) * 1995-03-22 2004-04-15 Hahn, Ortwin Verfahren zur Herstellung von Proben und Probenspannvorrichtung
ITPD20130235A1 (it) * 2013-08-12 2015-02-13 Geosec S R L Metodo, strumento, apparato e software per il monitoraggio dell'evoluzione di una fessura
WO2019108905A1 (en) * 2017-11-30 2019-06-06 University Of Kansas Fatigue crack detection using feature tracking
US11354814B2 (en) 2018-03-23 2022-06-07 University Of Kansas Vision-based fastener loosening detection
US11954844B2 (en) 2018-08-21 2024-04-09 University Of Kansas Fatigue crack detection in civil infrastructure

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US4063282A (en) * 1976-07-20 1977-12-13 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration TV fatigue crack monitoring system
US4136950A (en) * 1976-11-08 1979-01-30 Labrum Engineering, Inc. Microscope system for observing moving particles
US4163991A (en) * 1977-05-10 1979-08-07 U.S. Philips Corporation Arrangement for examining objects
US4185298A (en) * 1975-08-13 1980-01-22 Compagnie Industrielle Des Telecommunications Cit-Alcatel S.A. Process and apparatus for the automatic inspection of patterns
US4219847A (en) * 1978-03-01 1980-08-26 Canadian Patents & Development Limited Method and apparatus of determining the center of area or centroid of a geometrical area of unspecified shape lying in a larger x-y scan field
US4240109A (en) * 1976-10-14 1980-12-16 Micro Consultants, Limited Video movement detection
US4245243A (en) * 1976-08-25 1981-01-13 Kloeckner-Werke Ag System for registering and sorting out not properly filled deep-drawn packages in a packaging machine
US4249212A (en) * 1978-05-19 1981-02-03 Tokyo Broadcasting System Inc. Television picture special effects system using digital memory techniques

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DE1127606B (de) * 1953-10-20 1962-04-12 Dr Heimo Nielsen Spektralanalyseverfahren mit elektrisch-oszillographischer Aufzeichnung von Spektren
DE1128159B (de) * 1958-10-20 1962-04-19 Siemens Ag Anordnung zur Vielfachanzeige von Messwerten
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US3546377A (en) * 1968-06-12 1970-12-08 Ovitron Corp Video comparator using vidicons with delayed scanning
DE1914521B2 (de) * 1969-03-18 1975-12-04 Siemens Ag, 1000 Berlin Und 8000 Muenchen Zur Abbildung von Präparateinzelheiten dienendes Korpuskularstrahlgerät mit einer Fernseheinrichtung
US3683111A (en) * 1969-06-18 1972-08-08 Colorado Video Television bandwidth compression and expansion system
GB1279451A (en) * 1969-06-30 1972-06-28 Commw Of Australia Device for detecting change and motion in a given scene
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JPS5418145B1 (enrdf_load_stackoverflow) * 1971-06-08 1979-07-05
FR2212034A5 (enrdf_load_stackoverflow) * 1972-12-21 1974-07-19 Cem Comp Electro Mec
DE2439988A1 (de) * 1974-08-21 1976-03-04 Ford Werke Ag Verfahren und vorrichtung zur ermittlung von oertlich begrenzten formfehlern an gewoelbten flaechen
US3987241A (en) * 1974-10-17 1976-10-19 Westinghouse Electric Corporation Sampled differential analyzer

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4185298A (en) * 1975-08-13 1980-01-22 Compagnie Industrielle Des Telecommunications Cit-Alcatel S.A. Process and apparatus for the automatic inspection of patterns
US4063282A (en) * 1976-07-20 1977-12-13 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration TV fatigue crack monitoring system
US4245243A (en) * 1976-08-25 1981-01-13 Kloeckner-Werke Ag System for registering and sorting out not properly filled deep-drawn packages in a packaging machine
US4240109A (en) * 1976-10-14 1980-12-16 Micro Consultants, Limited Video movement detection
US4136950A (en) * 1976-11-08 1979-01-30 Labrum Engineering, Inc. Microscope system for observing moving particles
US4163991A (en) * 1977-05-10 1979-08-07 U.S. Philips Corporation Arrangement for examining objects
US4219847A (en) * 1978-03-01 1980-08-26 Canadian Patents & Development Limited Method and apparatus of determining the center of area or centroid of a geometrical area of unspecified shape lying in a larger x-y scan field
US4249212A (en) * 1978-05-19 1981-02-03 Tokyo Broadcasting System Inc. Television picture special effects system using digital memory techniques

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4486777A (en) * 1981-10-14 1984-12-04 Fuji Electric Company, Ltd. Defect detecting apparatus and method
US4528593A (en) * 1981-10-23 1985-07-09 Nicol James C B Visual sensor systems
US4581706A (en) * 1982-01-25 1986-04-08 Hitachi, Ltd. Method and apparatus for testing a joint
US4488648A (en) * 1982-05-06 1984-12-18 Powers Manufacturing, Inc. Flaw detector
US4653109A (en) * 1984-07-30 1987-03-24 Lemelson Jerome H Image analysis system and method
US4716459A (en) * 1985-01-25 1987-12-29 Nippon Kokan Kabushiki Kaisha Fatigue crack position detection apparatus
US4875170A (en) * 1986-04-10 1989-10-17 Hitachi, Ltd. Method and apparatus for estimating life expectancy of mechanical structures
US5060007A (en) * 1986-11-20 1991-10-22 Canon Kabushiki Kaisha Image blur display device
US5291279A (en) * 1990-08-27 1994-03-01 Toyoda Gosei Co., Ltd. Fatigue testing apparatus and method
US5539656A (en) * 1994-10-11 1996-07-23 United Technologies Corporation Crack monitoring apparatus
US5673203A (en) * 1994-10-11 1997-09-30 United Technologies Corporation Crack monitoring apparatus
KR100387197B1 (ko) * 2000-08-03 2003-06-12 주식회사 비솔 고속 결함 검출 시스템 및 방법
US20050074140A1 (en) * 2000-08-31 2005-04-07 Grasso Donald P. Sensor and imaging system
US7522745B2 (en) 2000-08-31 2009-04-21 Grasso Donald P Sensor and imaging system
US7321699B2 (en) 2002-09-06 2008-01-22 Rytec Corporation Signal intensity range transformation apparatus and method
US20070023485A1 (en) * 2005-07-29 2007-02-01 Snecma Method of repairing a blade of a one-piece bladed disc of a turbomachine and test piece for implementing the method
US7825348B2 (en) * 2005-07-29 2010-11-02 Snecma Method of repairing a blade of a one-piece bladed disc of a turbomachine and test piece for implementing the method
CN102661893A (zh) * 2012-05-08 2012-09-12 浙江工业大学 疲劳裂纹扩展试验摄像头安装调整机构
US20190064119A1 (en) * 2017-08-28 2019-02-28 Siemens Energy, Inc. Laser ultrasonic thermography inspection

Also Published As

Publication number Publication date
JPS6161616B2 (enrdf_load_stackoverflow) 1986-12-26
NL181755C (nl) 1987-10-16
FR2463926A1 (fr) 1981-02-27
FR2463926B1 (enrdf_load_stackoverflow) 1983-11-10
JPS5635006A (en) 1981-04-07
NL181755B (nl) 1987-05-18
GB2057124A (en) 1981-03-25
NL8004756A (nl) 1981-02-25
DE2934038A1 (de) 1981-03-26
GB2057124B (en) 1983-07-06
DE2934038C2 (de) 1982-02-25

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